Components

Chartjs

GitHub

A Stimulus controller to deal with chart.js.

Installation

  1. Install the package

    Terminal
    $ yarn add @stimulus-components/chartjs

  2. Register the controller in your application

    app/javascript/controllers/index.js
    import { Application } from '@hotwired/stimulus'
import Chartjs from '@stimulus-components/chartjs'

const application = Application.start()
application.register('chartjs', Chartjs)

This component is based on the Chart.js library.

Example

Chartjs

Usage

Basic usage

app/views/index.html
<canvas
  data-controller="chartjs"
  data-chartjs-data-value='{ "labels": ["January", "February", "March", "April", "May", "June", "July"], "datasets": [{ "label": "My First dataset", "backgroundColor": "transparent", "borderColor": "#3B82F6", "data": [37, 83, 78, 54, 12, 5, 99] }] }'
></canvas>

If you extend this controller, it could be handy to use it with a target:

app/views/index.html
<div
  data-controller="chartjs"
  data-chartjs-data-value='{ "labels": ["January", "February", "March", "April", "May", "June", "July"], "datasets": [{ "label": "My First dataset", "backgroundColor": "transparent", "borderColor": "#3B82F6", "data": [37, 83, 78, 54, 12, 5, 99] }] }'
>
  <canvas data-chartjs-target="canvas"></canvas>

  <!-- You need to define this action -->
  <button data-action="chartjs#update">Update me!</button>
</div>

It's much simpler with a framework.

With backend framework (optional)

app/controllers/charts_controller.rb
class ChartsController < ApplicationController
  def index
    @chart_data = {
      labels: %w[January February March April May June July],
      datasets: [{
        label: 'My First dataset',
        backgroundColor: 'transparent',
        borderColor: '#3B82F6',
        data: [37, 83, 78, 54, 12, 5, 99]
      }]
    }

    @chart_options = {
      scales: {
        yAxes: [{
          ticks: {
            beginAtZero: true
          }
        }]
      }
    }
  end
end
app/views/index.html
<canvas
  data-controller="chartjs"
  data-chartjs-data-value="<%= @chart_data.to_json %>"
  data-chartjs-options-value="<%= @chart_options.to_json %>"
></canvas>

Configuration

AttributeDefaultDescriptionOptional
data-chartjs-data-value{}The data for Chart.js❌
data-chartjs-type-valuelineType of the chart✅
data-chartjs-options-value{}The options for Chart.js✅

Extending Controller

You can use inheritance to extend the functionality of any Stimulus component:

app/javascript/controllers/chartjs_controller.js
import Chartjs from "@stimulus-components/chartjs"

export default class extends Chartjs {
  connect() {
    super.connect()
    console.log("Do what you want here.")

    // The chart.js instance
    this.chart

    // Options from the data attribute.
    this.options

    // Default options for every charts.
    this.defaultOptions
  }

  // Bind an action on this method
  async update() {
    const response = await fetch("https://example.com/chart_data.json")
    const data = await response.json()

    this.chart.data = data
    this.chart.update()
  }

  // You can set default options in this getter for all your charts.
  get defaultOptions() {
    return {
      maintainAspectRatio: false,
      legend: {
        display: false,
      },
    }
  }
}

This controller will automatically have access to targets defined in the parent class.

If you override the connect, disconnect or any other methods from the parent, you'll want to call super.method() to make sure the parent functionality is executed.